My last day working was Friday, Dec 29, 2017. Sunday, Dec 31, 2017 was my "official" date of retirement. Monday was Jan 1 . . . New Years Day, so historically, the end of a 3 day weekend. I woke up Tuesday morning and my first thought was "now what?".
So . . . welcome to the club . . . you'll figure it out. Just take your time, relax and do what you want to when you want to.